英文翻譯：超高層建筑結構橫向風荷載效應

1、武漢科技大學本科畢業(yè)設計外文翻譯Across-wind loads and effects of super-tall buildings and structuresGU Ming & QUAN Yong SCIENCE CHINA Technological Sciences,2011,54(10):25312541超高層建筑結構橫向風荷載效應顧明 全勇中國科學 技術科學，2011，54(10):25312541摘 要隨著建筑高度的不斷增加，橫

2、向風荷載效應已經成為影響超高層建筑結構設計越來越重要的因素。高層建筑結構的橫向風荷載效應被認為由空氣湍流，搖擺以及空氣流體結構相互作用所引起的。這些都是非常復雜的。盡管30年來，研究人員一直關注這個問題，但橫向風荷載效應的數據庫以及等效靜力風荷載的計算方法還沒有被開發(fā)，大多數國家在荷載規(guī)范里還沒有相關的規(guī)定。對超高層建筑結構的橫向風荷載效應的研究成果主要包括橫向風荷載的動力以及動力阻尼的測定，數據庫的開發(fā)和等效靜力風荷載的理論方法的等等。在本文中，我們首先審查目前國內外關于超高層建筑結構風荷載的影響的研究。然后我們在闡述我們的研究成果。最后，我們會列舉我們研究成果在超高層建筑結構中應用的的案例

3、。1 引言隨著科技的發(fā)展，建筑物也越來越長、高、大，越來越對強風敏感。因此，風工程研究人員面臨著更多新的挑戰(zhàn)，甚至一些未知的問題。例如，超高層建筑現在在全世界普遍流行。高度為443米的芝加哥希爾斯塔保持了是世界上最高建筑物26年的記錄，現在還有幾十個超過400米的超高層建筑被建造。828米高的迪拜塔已經建造完成。在發(fā)達國家，甚至有人建議建造數千米的“空中城市”。隨著高度的增加，輕質高強材料的使用，風荷載效應特別是具有低阻尼的超高層建筑橫向風動力響應將變得更加顯著。因此，強風荷載將成為設計安全的超高層建筑結構中的一個重要的控制因素。達文最初引入隨機的概念和方法應用發(fā)哦順風向荷載效應的建筑物和其他

4、結構的抗風研究。之后，研究人員完善了相關的理論和方法，并且主要的研究成果已經反映在一些國家的結構設計荷載規(guī)范里。對現代超高層建筑結構，橫風向風荷載的作用可能已經超過順風向荷載效用。雖然研究人員已經關注這個方向已經30多年了，但能夠被廣泛接受的橫風向荷載數據庫以及等效靜力荷載的計算方法還沒有形成。只有少數國家在他們的荷載規(guī)范里有相關的內容和規(guī)定。因此，研究超高層建筑結構橫風向風振和等效靜力荷載在超高層建筑設計領域內具有重要的理論意義和實用價值。 2 研究現狀2.1 橫風向荷載及作用機制 過去的研究主要集中在橫風向荷載機制。郭指出橫風向荷載的激發(fā)主要由于被公認為空氣動力阻尼的尾

5、流、空氣湍流以及風荷載耦合作用。索拉里認為橫風向荷載主要由于尾流的原因所引起?？ɡ锬仿暦Q橫風向的效應主要是由分離剪切層和尾流波動引起的橫向均勻壓力波動所引起的。目前，高層建筑橫風向荷載機制已被人為是流入湍流激發(fā)、尾流激發(fā)、以及氣動彈性影響。湍流以及尾流激勵一般是外部空氣動力，在本文章中，所涉及的統稱為空氣動力。同時，氣體的彈性效應可以被認為是氣體動力阻尼。橫風向氣體動力不再像順向風一樣符合準穩(wěn)態(tài)假設。因此，橫向風荷載譜不能直接作為一個脈動風速譜。對不穩(wěn)定風壓力來說，風洞試驗技術是目前研究橫向風動力的主要技術。風洞試驗技術主要包括氣體彈性模型試驗、高頻力平衡試驗以及對多點壓力測量的剛性模型實驗技

6、術。用橫風向外部動力，橫風向氣動阻尼，橫向風響應和建筑結構等效靜力風荷載的數據可以對超高層建筑結構進行計算。2.2 橫風向氣動力 如上所述，橫風向氣動力基本上可以通過以下途徑獲得：從氣動彈性模型在一個風洞的橫風向響應確定橫風向氣動力；通過剛性模型風壓空間一體化獲得橫向風動力；使用高頻測力天平技術測量基底彎矩來獲得廣義的氣動力。 2.2.1 從氣動彈性模型的動態(tài)響應確定橫風向氣動力這種方法采用的是氣動彈性模型的橫風向風振響應，結合動態(tài)特性的模型識別橫風向氣動力。墨爾本對對一系列圓形、方形、六角形、多邊形沿高度分布進行氣動彈性模型風洞試驗。然而進一步試驗表明您橫風向氣動阻力與氣

7、動力混合在一起，使他難以準確地提取氣動阻尼力。因此，該方法很少使用。2.2.2 風壓積分法 研究人員建議用風壓積分法獲取更準確的高層建筑橫風向氣動力。伊斯蘭等人采用這種方法得到橫風向氣動力，陳等人研究了典型建筑結構在不同風場條件橫風向氣動力。影響橫風向氣動力的因素主要有湍流強度、湍流尺度。湍流強度被發(fā)現擴大帶氣動力和降低峰值。然而,湍流強度被認為對總能量幾乎沒有影響。因此,研究人員在某種程度上已經意識到了在風力條件定量規(guī)則的變化橫風氣動力。梁等人使用這種方法檢查了建筑物上的典型矩形邊界層風洞橫風向氣動力，從而提出高大的建筑物的經驗公式和橫風向動態(tài)響應模型。結果表明, 橫風向

8、湍流對于橫風向氣動力的貢獻比那些激勵要小的多?；诖罅康慕Y果,導出橫風向湍流激勵和激發(fā)后的PSD計算公式。第一廣義的橫風向氣動力計算可以通過在剛性建筑模型整合壓力分布得到，這是該方法一個重要的優(yōu)越性。然而,考慮到在這類方法需要大量的大規(guī)模的結構測壓，同步測量風壓是很難實現的。此外,對于建筑和結構復雜的配置,準確的風壓分布和空氣動力難以使用這種方法。2.2.3 高頻測力平衡技術 與壓力測量技術相比，高頻力平衡技術對于得到總氣動力有其獨特的優(yōu)勢，檢測和數據分析過程都很簡單。因此這項技術通常應用于初期設計階段的建筑外觀的選擇。目前這項技術被廣泛應用于作用在超高層建筑結構的全風荷載以及動力響

9、應計算。高頻力平衡技術自從1970年已經逐漸發(fā)展起來。賽馬可等人是第一批把此技術應用到模型測量的人。他們最初提出平衡模型系統應有一個比風力頻率更高的固有頻率。由常和達文發(fā)展的平衡技術標志著平衡設備的成熟。 卡里姆進行了一項實驗研究。對于在城市和郊區(qū)具有不同截面形式的高層建筑的橫風向氣動力研究表明對于建筑物風的不確定以及結構參數對橫風向空氣動力的設計有很小的影響并且順風向和橫風向氣動力或扭矩之間的聯系時微不足道的。但橫風向動力和扭矩之間的聯系是非常密切的。這個結論對于三維方向精確的風荷載模型是很重要的。特別是石和全等人做了一系列關于矩形建筑的邊率，建筑物橫截面形狀，建筑的面率的效應以及

10、用五元平衡的高層建筑橫風向動力設計的風域條件。事實上，基于大量的風隧道檢測結果典型高層建筑橫風向氣動力系數的公式已經被我們建立了。2.3 橫風向氣動阻尼 1978年卡里姆對基于氣動彈性模型技術和風壓積分法的高層建筑橫風向動力響應做了一次調查研究。他指出由在一定范圍內風壓力測試獲得的橫風向氣動力計算而得到的橫風向風振響應總是比那些相同建筑模型的氣動彈性模型要小。這個重要的研究成果使得研究人員認識到橫風向氣動負阻尼的存在。 后來，研究人員對這個問題進行了大量的研究并且找到了有效的方案來確定氣動阻尼。第一種方法是通過比較基于來自剛性模型試驗和氣動彈性模型試驗的氣動力所得到的到哪個

11、臺響應。第二種方法是從由氣動彈性模型或強迫振動模型所得到的總氣動力中分離出氣動阻力。第三種方法是從氣動彈性模型分離氣動阻尼的的識別方法。此外，研究人員意識到風因素的影響規(guī)律。這些因素包括結構形狀、結構動力參數、風條件等等?？ɡ锬返热耸堑谝慌岢鐾ㄟ^比較來確定氣動阻尼的方法。陳等人采用這種技術來研究橫風向效應和高層建筑結構的動態(tài)阻尼并提出了一個氣動阻尼公式。 史迪克最初制造了一批測定總氣動力、氣動阻尼力與氣動力的強迫振動測量設備。他測量高層建筑模型基底彎矩是通過一個專門的設計裝置產生振動所產生的有關的氣動力從總氣動力脫離進而分解為氣動應力和氣動阻尼力獲得氣動阻尼?？虏噲D對諧波振動建筑

12、模型測量風壓獲得總氣動力。然后用類似史迪克的方法計算空氣阻尼。這種方法的優(yōu)點是真實的建筑特性并非必須被考慮到。這種方法更方便更實用，特別是在推廣實驗結果。這種方法的的主要缺點是它需要復雜的設備，尤其是直到現在多元耦合裝置是不可用的。 確定氣動阻尼的隨機振動響應的氣動彈性模型課采用適當的系統識別技術，其中包括頻域法，時域的方法以及時域頻域的方法。在這些方法中隨機減量法、時域方法被廣泛采用以確定高層建筑的氣動阻尼。杰瑞介紹隨機減量法來識別結構阻尼。馬克采用隨機減量法確定高層建筑順橫風向氣動阻尼。他們分析了影響建筑長寬比、邊比、氣動阻尼、結構阻尼。田村等人用隨機減量技術確定超高層建筑氣動阻

13、尼。全等人通過實驗確定在不同的風領域具有不同結構中阻尼方形截面的橫風向氣動阻尼，并得出了一個經驗公式。這些研究成果已通過相關的中國規(guī)范。秦和谷是第一個引入隨機空間識別方法于氣動參數的確認的研究人員。這些氣動參數包括大跨度橋梁氣動剛度和阻尼。于隨機變量法相比，隨機空間識別方法具有更多的優(yōu)點。它能克服隨機變量法的弱噪音抵抗力和需要大量實驗數據的缺點。秦采用這種方法來確定高層建筑的氣動阻尼。2.4規(guī)范的實用性 如上所說，雖然研究者一直關注高層建筑風荷載超過30年了，但被廣泛接受的橫風向風荷載數據庫和計算方法，等效靜力風荷載尚未開發(fā)。此外，只有少數國家采用相關的規(guī)定和代碼。于其他國家相比，日

14、本建筑協會提供了計算高層建筑結構橫風向荷載的最好方法。然而公式的橫風向代碼知適用于高層建筑高寬比小于六，這似乎很難滿足實際需要。而且此方法在這種方法里氣動阻尼沒有被考慮。 在目前的中國建筑結構荷載規(guī)范只提供了一個簡單的方法來計算渦激共振的高聳結構，而一般不適用于高層建筑結構抗風設計。在題為“高層建筑鋼結構設計詳細說明”里，我們的研究成果已經通過。2.5 總結 隨著建筑高度不斷增加，橫風向荷載效應已經成為超高層建筑結構設計的重要因素。目前，對超高層建筑結構橫風向荷載的研究主要包括橫風向風荷載的機制，橫風向氣動力、氣動阻尼和在規(guī)范中的應用。因此我們的一些研究成果主要有典型建筑結

15、構的橫風向力，氣動阻尼以及在中國規(guī)范的應用。最后介紹了典型的案例，在這個案例中建造更高層建筑的趨勢預示著風工程研究人員將面臨著更多更新的挑戰(zhàn)，甚至到現在他們都沒有意識到的問題。因此需要更多地努力去解決工程設計問題，同時進一步發(fā)展風工程。附件：英文原文Across-wind loads and effects of super-tall buildings and structuresGU Ming & QUAN YongAbstractAcross-wind loads and effects have become increasingly important factors in

16、the structural design of super-tall buildings and structures with increasing height. Across-wind loads and effects of tall buildings and structures are believed to be excited by inflow turbulence, wake, and inflow-structure interaction, which are very complicated. Although researchers have been focu

17、sing on the problem for over 30 years, the database of across-wind loads and effects and the computation methods of equivalent static wind loads have not yet been developed, most countries having no related rules in the load codes. Research results on the across-wind effects of tall buildings and st

18、ructures mainly involve the determination of across-wind aerodynamic forces and across-wind aerodynamic damping, development of their databases, theoretical methods of equivalent static wind loads, and so on. In this paper we first review the current research on across-wind loads and effects of supe

19、r-tall buildings and structures both at home and abroad. Then we present the results of our study. Finally, we illustrate a case study in which our research results are applied to a typical super-tall structure.1 Introduction With the development of science and technology, structures are becoming la

20、rger, longer, taller, and more sensitive to strong wind . Thus, wind engineering researchers are facing with more new challenges, even problems they are currently unaware of. For example, the construction of su-per-tall buildings is now prevalent around the world. The Chicago Sears Tower with a heig

21、ht of 443 m has kept the record of the worlds tallest building for 26 years now. Dozens of super-tall buildings with heights of over 400 m are set to be constructed. Burj Dubai Tower with a height of 828 m has just been completed. In developed countries,here are even proposals to build “cities in th

22、e air” with thousands of meters of magnitude. With the increase in height and use of light and high-strength materials, wind-induced dynamic responses, especially across-wind dynamic responses of super-tall buildings and structures with low damping, will become more notable. Hence, strong wind load

23、will become an important control factor in designing safe super-tall buildings and structures. Davenport initially introduced stochastic concepts and methods into wind-resistant study on along-wind loads and effects of buildings and other structures. Afterward, researchers developed related theories

24、 and methods 817, and the main research results have already been reflected in the load codes of somecountries for the design of buildings and structures 1823. For modern super-tall buildings and structures, across-wind loads and effects may surpass along-wind ones. Al-though researchers have been f

25、ocusing on the complex problem for over 30 years now, the widely accepted data-base of across-wind loads and computation methods of equivalent static wind loads have not been formed yet. Only a few countries have accordingly adopted the related con-tents and provisions in their codes 18, 20. Therefo

26、re, studying across-wind vibration and the equivalent static wind loads of super-tall buildings and structures is of great theoretical significance and practical value in the field of structural design of super-tall buildings and structures. The current paper thus reviews the research situation of a

27、cross-wind loads and effects of super-tall buildings and structures both at home and abroad. Then, the research results given by us are presented. Finally, a case study of across-wind loads and effects of a typical super-tall structure is illustrated.2 Research situation 2.1 Mechanism of across-wind

28、 loads and effects Previous researches focused mainly on the mechanism of across-wind load. Kwok 2426 pointed out that across-wind excitation comes from wake, inflow turbulence, and wind-structure interaction effect, which could be recog-nized as aerodynamic damping. Solari 27 attributed the across-

29、wind load to across-wind turbulence and wake exci-tations, considering wake as the main excitation. Islam et al. 28 and Kareem 13 claimed that across-wind responses are induced by lateral uniform pressure fluctuation due to separation shear layer and wake fluctuation. Currently, the mechanism of acr

30、oss-wind load on tall buildings and struc-tures has been recognized as inflow turbulence excitation, wake excitation, and aeroelastic effect. Inflow turbulence and wake excitation are essentially the external aerody-namic force, which is collectively referred to in the present paper as aerodynamic f

31、orce. Meanwhile, aeroelastic effect can be treated as aerodynamic damping. Across-wind aero-dynamic force no longer conforms to quasi-steady assump-tion as the along-wind one; thus, the across-wind force spectra cannot be directly expressed as a function of inflow fluctuating wind velocity spectra.

32、Wind tunnel test tech-nique for unsteady wind pressures or forces is presently a main tool for studying across-wind aerodynamic forces. The wind tunnel experiment technique mainly involves the aeroelastic building model experiment technique, high fre-quency force balance technique, and rigid model e

33、xperiment technique for multi-point pressure measurement. Using data of across-wind external aerodynamic force and across-wind aerodynamic damping, across-wind responses and the equivalent static wind load of buildings and structures can be computed for the structural design of super-tall buildings

34、and structures.2.2 Across-wind aerodynamic force As stated above, the across-wind aerodynamic force can be obtained basically through the following channels: (i) iden-tifying across-wind aerodynamic force from across-wind responses of an aeroelastic building model in a wind tunnel; (ii) obtaining ac

35、ross-wind aerodynamic force through spa-tial integration of wind pressure on rigid models; (iii) ob-taining generalized aerodynamic force directly from meas-uring base bending moment using high frequency force balance technique. 2.2.1 Identification of across-wind aerodynamic force from dynamic resp

36、onses of aeroelastic building model This method employs across-wind dynamic responses of the aeroelastic building model, combining the dynamic charac-teristics of the model to identify across-wind aerodynamic force. Saunders 29, Kwok 24, Kwok and Melbourne 30, Kwok 25, and Melbourne and Cheung 31 pe

37、rformed aeroelastic model wind tunnel tests on a series of circular, square, hexagon, polygon with eight angles, square with reentrant angles and fillets, and tall or cylindrical structures with sections contracting along height. However, further studies showed that across-wind aerodynamic damping f

38、orce and aerodynamic force mixed together make it diffi-cult to extract aerodynamic damping force accurately. As such, the method has been seldom used. 2.2.2 Wind pressure integration method Researchers have recommended wind pressure integration to obtain more accurately the across-wind aerodynamic

39、forces on tall buildings. Islam et al. 28, Cheng et al. 32, Nishimura and Taniike 33, Liang et al. 34, 35, Ye 36, Tang 37, Zhang 38, and Gu et al. 39 adopted this method to obtain across-wind aerodynamic forces on tall buildings and structures. Cheng et al. 32 experimentally studied across-wind aero

40、dynamic forces of typical buildings under different wind field conditions and derived empirical formulas for the power spectrum density (PSD) of the across-wind aerodynamic force reflecting the effects of tur-bulent intensity and turbulent scale. Turbulent intensity was found to widen the bandwidth

41、of PSD of the across-wind aerodynamic force and reduce the peak value. However, tur-bulent intensity was determined to have almost no effects on total energy. Thus, researchers have recognized the quantita-tive rules of variation of across-wind aerodynamic force with wind condition to some extent. L

42、iang et al. 34, 35 examined across-wind aerodynamic forces on typical rectangular buildings in a boundary layer wind tunnel using this method, thus proposing empirical formulas for PSD of across-wind aerodynamic forces of tall rectangular buildings and an ana-lytical model for across-wind dynamic re

43、sponses. Ye 36 and Zhang 38 decomposed across-wind turbulence excita-tion and vortex shedding excitation in across-wind aerody-namic forces on typical super-tall buildings. The resultsshowed that the across-wind turbulence contributed much less to across-wind aerodynamic force than the wake excita-t

44、ion. Based on a large number of results, we derived PSD formulas for the across-wind turbulence excitation and the wake excitation, and further derived a new formula for the across-wind aerodynamic force. The first- and higher-mode generalized across-wind aerodynamic forces can be calculated through

45、 the integra-tion of pressure distribution on rigid building models, which is an important advantage of this method. However, given the need for a large number of pressure taps for very large-scale structures in this kind of method, synchronous pressure measurements are difficult to make. Moreover,

46、for buildings and structures with complex configurations, ac-curate wind pressure distribution and aerodynamic force are difficult to obtain using this kind of method. 2.2.3 High frequency force balance technique Compared with the pressure measuring technique, high fre-quency force balance technique

47、 has its unique advantage for obtaining total aerodynamic forces. The test and data analy-sis procedures are both very simple; hence, this technique is commonly used for selection studies on architectural ap-pearance in the initial design stage of super-tall buildings and structures. Currently, this

48、 technique is widely used for total wind loads acting on super-tall buildings and structures, and for dynamic response computation as well. The high frequency force balance technique has been gradually developed since the 1970s. Cermak et al. 40 were the first to use this technique for building mode

49、l measurement. They initially pointed out that the bal-ance-model system should have a higher inherent frequency than the concerned frequency of wind forces. The five-component balance developed by Tschanz and Daven-port 41 marked the maturity of balance facility. Kareem conducted an experimental st

50、udy on across- wind aerodynamic forces on tall buildings with various sec-tion shapes in urban and suburban wind conditions. The research showed that for the buildings with aspect ratios of 46, uncertainties of wind and structural parameters have small effects on PSD of the across-wind aerodynamic f

51、orce, and the correlation between the along-wind aerodynamic force and the across-wind aerodynamic force or the torsion moment is negligible, but there is a strong correlation be-tween the across-wind aerodynamic force and the torsion moment. This conclusion is important for the development of three

52、-dimensional refined wind load model. Particularly, Gu and Quan 42 and Quan et al. 43 made detailed stud-ies on the effects of the side ratio of a rectangular building, cross-section shape of a building, aspect ratio of a building, and wind field condition on the PSD of the across-wind aerodynamic f

53、orce of tall buildings using a five-component balance. In fact, based on a large number of wind tunnel test results, formulas for across-wind aerodynamic force coeffi-cients of the typically tall buildings have been derived by us and other researchers, some of which are listed in Table 1. In additio

54、n, in Table 1, the formula derived by Gu and Quan 42 has already been adopted in related design codes in China.2.3 Across-wind aerodynamic damping In 1978, Kareem 44 performed an investigation on across-wind dynamic responses of tall buildings based on both of the aeroelastic model technique and the

55、 wind pres-sure integration method. He found out that the across-wind dynamic responses calculated with the across-wind aerody-namic forces obtained from the wind pressure tests at a certain test wind velocity range were always smaller than those of the aeroelastic model of the same building model.

56、This important result made researchers realize the existence of across-wind negative aerodynamic damping.Subsequently, researchers carried out numerous studies on the problem and developed effective methods for identi-fying aerodynamic damping. The first kind of method ob-tains aerodynamic damping b

57、y comparing the dynamic re-sponses computed based on the aerodynamic forces from rigid building model tests and those from aeroelastic model tests. The second one separates aerodynamic damping force from the total aerodynamic force measured from aeroelastic building models or forced vibration buildi

58、ng models. The third kind employs identification methods for extracting aerodynamic damping from random responses of aeroelastic models. Moreover, researchers realized the effect law of factors, including structural shape, structural dynamic pa-rameters, wind conditions, and so on, on aerodynamic da

59、mping, Isyumov et al. 45 were the first researchers to propose a method for aerodynamic damping through com-paring responses from a rigid building model test using HFFB technique with those of an aeroelastic model of the same building. Cheng et al. 46 adopted the method to study across-wind responses and aerodynamic damping of tall square buildings and proposed an aerodynamic damping formula.Steckley